botsapper == I'm now a big fan of Indonesian Vespa Ekstrim videos, although the one you posted is in many ways the best.

On topic: The seating position didn't change much because you head and neck are narrow, compared to the windshield, which wasn't lowered. I think it's a good first step, though. How much will you lose back to padding?

Yes, I've been reading about how they did Terry's bike over on Craig Vetter's page. That's one reason I wanted to see if I could lower the seat. That was sort of a major change they did on Terry's Zero.

So, today I MAY have started tearing off the back of the motorcycle....

To get the trunk off, I had to remove the plug from the charging cord, pull it through, and then wire it back on again. The wire harness for the tail light and turn signals is all zip-tied to the steel framework of the trunk. A side-cutters made quick work of getting the wire harness off.

Once I got the trunk off, I used the two bolts that held it on to instead hold on a 1x2" board.

With one on either side, I could then add a cross piece and build a ladder-back chair.

If I wanted to do a real, full-blown stream-liner, one concern that I have is swapping out lighting. The headlamp is a standard 12v bulb, but the rest is dedicated 4V LED lighting. I wouldn't easily be able to replace the tail and turn signals with more typical 12V LED lights. (The DC/DC output on the bike is pretty minimal, and it switches 4v power for the brake light and turn signals.)

One thing that I thought might be possible is to keep the stock tail and turn signals, but have them mounted at about my shoulder height.

For right now, I remounted them on a piece of wood, lower. That way, the plastic piece that I don't want to cut off (at least for now) doesn't poke me, and the wire harness easily reaches without modification.
As far as I can tell, this seems street legal for testing around my neighborhood. I screwed the license plate to the back of the upper cross-member.

Sitting in a recumbent position, the backrest is actually really comfortable. The handlebars are a little too far away though.

After monkeying around a bit, I WAS able to figure out how to get all the trim off the handlebars and see what's actually under there. It looks like pretty normal handlebar stuff. I think I should be able to loosen the four middle screws and tilt the handles towards me. I'm not sure if that will be enough or not. If not, replacing it with a different shape/length handlebar shouldn't be too tough.

The wood framing is taller than it needs to be right now. However, it's also a nice point to begin experimentally attaching tail material.

On the Craig Vetter streamliners, he bases the angle of the tail on being a right angle from this "backrest" bulkhead. I'm not sure if that will be too steep or not, but it's something to start from.

It's built from a fiberglass bulkhead that I got from Craig Vetter, angle aluminum, and coroplast.

I'm just finishing up the frame right now, and will hopefully be installing the coroplast today.

I moved the tail light and turn signals from the back of the scooter to behind the head-rest. The wire-harness for the lights just exactly reaches there!

The main reason for the tail is really more for cargo than for aerodynamics. I'm leaving in just a few days for a 1,000+ mile trek on my electric motorcycle. I need room for tent and sleeping bag, clothes, big video camera backpack and tripod, etc.

I can't remember precisely who it was but I think it was someone commenting on a Vetter forum, said that he experienced a LOT less buffeting on his helmet when the tail fairing was in place. Made for a much less fatiguing ride.

It strikes me that cutting your dad's canoe in half and just screwing one half to the tail of your bike might be close to what you need.

I rode a yamaha majesty for several years, very similar in size but a 400cc petrol engine. While I think your efficency ideas are great, what you have built looks very dangerous to me. A side wind, gust from a truck going the other way... they are really going to push you around much more now. I would be concerned about riding on normal roads with that.